If we can't be bothered to vote in the primaries, wjy would anyone believe us that a progressive candidate would somehow lure millions more to vote?
As I know the comments will be, uhhh, fun, I've turned off reply notifications.
It's by state: https://ballotpedia.org/Primary_election_types_by_state
I think semi-closed the way it is implemented in MA is the best. You can request a primary ballot for either party but not both, regardless of what your voter registration says.